Rates of multidrug-resistant organisms (MDRO) are among the highest in persons requiring maintenance hemodialysis (MHD). Antimicrobial exposure is the main risk factor for the emergence and spread of MDRO. Up to 30% of antimicrobials administered in out-patient dialysis facilities are not indicated. Decreasing inappropriate, unnecessary or suboptimal antimicrobial use in dialysis facilities is therefore crucial. We recently published a decision analytic model on the clinical and economic consequences of implementing antimicrobial stewardship programs (ASP) in out-patient dialysis facilities nation-wide. The model predicted a 4.8% reduction in infections caused by MDRO and Clostridium difficile; a 4.6% reduction in infection-related deaths and a 5.0% reduction in costs. In 2017, the PI completed an AHRQ-funded study of an ASP in out-patient dialysis facilities. The program, which focused on educational and behavioral strategies, resulted in a reduction in antimicrobial use (P=0.02). Although successful, three barriers to even greater effective prescribing were identified. First, our initial ASP method could not fully identify inappropriate doses, administered after the empiric doses, in a timely manner. Thus, opportunities for improving prescribing were missed. Second, approximately 55% of doses prescribed were from orders received from the transferring hospital upon hospital discharge. Data pertaining to the indications for and choice of antimicrobial therapy were minimal and thereby limited the number of opportunities to improve antimicrobial prescribing. Third, engagement from unit medical directors was minimal. Lack of leadership support likely prevented the ASP to be more effective. With this foundation and leveraging a research infrastructure established during our previous AHRQ grant, this proposal, entitled OPTIMUS (Optimizing Antimicrobial Use In Maintenance Dialysis UnitS), will develop and implement an improved ASP. In addition to the previous educational and behavioral components, specific tools and strategies to overcome the three barriers mentioned above will be developed and implemented in this improved ASP. These tools include an antimicrobial hospital transfer report and an evidence-based checklist for antimicrobial prescribing in the dialysis facilities. We will enroll DaVita dialysis units and have already obtained leadership support. Our interdisciplinary team includes investigators with expertise in ASP and implementation science, senior nephrologists with experience in quality improvement initiatives and our CDC consultant, with expertise in MHD healthcare quality. An interrupted time series design will be used in 8 intervention and 8 control units. Specific aims are:1] To develop and implement an improved ASP in out-patient hemodialysis units, 2] To demonstrate the effectiveness of this ASP in reducing antimicrobial use, and 3] To develop a dialysis setting specific-antimicrobial prescribing audit tool and demonstrate improvement in the quality of antimicrobial prescribing patterns as a result of the ASP. Demonstrating the efficacy of this ASP and generating tools to assist in optimizing antimicrobial prescribing will provide an unmet and overdue need in the MHD population and will ultimately improve their health outcomes.